The Role of the Ocean Carbon Cycle in Climate Change

The ocean carbon cycle plays a twofold role in the context of climate change: (1) through carbon dioxide gas exchange with the atmosphere and carbon cycle climate feedbacks, the ocean regulates the carbon dioxide concentration in the atmosphere and hence has a strong influence on the heat budget of the Earth; (2) the paleo-climatic marine sediment core record is largely based on biogenic matter fluxes from the ocean surface to the sea floor, which are part of the marine carbon cycle. The ocean is important for global carbon cycling, primarily due to three factors: (1) the ocean is a huge carbon reservoir with a relatively short turnover time; (2) carbon dioxide in sea water is effectively dissociated inorganically into other substances; (3) marine plankton is keeping the surface ocean carbon dioxide concentration at a lower level than would a lifeless ocean. On intermediate to long time scales, the ocean provides the most important sink for anthropogenic carbon dioxide. The marine uptake kinetics for carbon dioxide work on a longer time scale than current and projected emissions by humans.